In order to ensure the mobility of vehicles irrespective of external influencing forces, vehicles are suitably motorized. For this purpose prime movers are used, which are mainly integrated into the vehicles, but may also be arranged thereon. For the most part internal combustion engines are used as prime movers, although these are increasingly being supplemented or even replaced by electric motors.
Purely electric vehicles typically have a smaller range than vehicle using internal combustion engine, due to the limited energy density of batteries or other energy accumulators in the electric vehicles. Moreover, electric vehicle batteries are a cost-intensive technology and make inexpensive series production difficult. Hybrid vehicles in series production are may have reduced fuel consumption. However, this reduced fuel consumption may come at a higher purchase price than an equivalent vehicle using only an internal combustion engine for motive power.
Measures for reducing the fuel consumption in conventional vehicles may be directed towards purposely shutting off the internal combustion engine. These engines may therefore shut off by an automatic start-stop system, particularly in stationary phases, in the absence of any torque demand. In vehicles with manual shift transmission, a start signal is then triggered through the actuation of the clutch pedal, for example, which restarts the internal combustion engine. Where automatic transmissions are used, this start signal is generated, for example, by lifting the brake pedal or cancelling an alternative brake actuation device.
Additionally, small electric motors may be integrated into vehicles with internal combustion engine to provide electric boosting without a substantial increase in vehicle cost. In such a vehicle, the electrical drive mode the electric motor may drive at least one drive axle of the vehicle, whilst the internal combustion engine is at a standstill. In these vehicles, the internal combustion engine is coupled to another drive axle. The electric motor may also be used to charge a battery during some vehicle operating conditions.
However, the Inventors have recognized several drawbacks with this type of vehicle. For instance, it may be costly to separately connect the electric motor one drive axle and the internal combustion engine to another drive axle. Moreover, coupling the electric motor and internal combustion engine to the drive axles in this way may increase the bulkiness of the vehicle. Furthermore, the electric motor cannot crank the engine in this type of vehicle.
As such, a method for operating a vehicle system is provided. The method includes activating a starter-generator rotationally coupled to a crankshaft output in an internal combustion engine while combustion operation in the internal combustion engine is inhibited, operating the starter-generator to drive the crankshaft in a predetermined speed range while combustion operation in the internal combustion engine is inhibited, and activating combustion operation in a cylinder of the internal combustion engine in response to a combustion activation trigger. In this way, the starter-generator may be used to drive the crankshaft at an idle speed without operation of the internal combustion engine, for example. It will be appreciated that this method may be implemented when the vehicle is stopped for a short duration, for instance. As a result, fuel consumption and vehicle emission are reduced, thereby improving vehicle operation. It will be appreciated that this method may be used in an internal combustion having a clutch and a manual shift transmission. Consequently, the vehicle system may be inexpensively integrated into existing engines, if desired, thereby reducing manufacturing costs of the vehicle system.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.